uint256::GetCheapHash bigendian compatibility

Author: arowser

src/uint256.h

@@ -12,6 +12,7 @@
 #include <stdint.h>
 #include <string>
 #include <vector>
+#include "crypto/common.h"
 
 /** Template base class for fixed-sized opaque blobs. */
 template<unsigned int BITS>
@@ -119,13 +120,10 @@ class uint256 : public base_blob<256> {
      * used when the contents are considered uniformly random. It is not appropriate
      * when the value can easily be influenced from outside as e.g. a network adversary could
      * provide values to trigger worst-case behavior.
-     * @note The result of this function is not stable between little and big endian.
      */
     uint64_t GetCheapHash() const
     {
-        uint64_t result;
-        memcpy((void*)&result, (void*)data, 8);
-        return result;
+        return ReadLE64(data);
     }
 
     /** A more secure, salted hash function.